Categorizing Uses of Communications Metadata - Systematizing Knowledge and Presenting a Path for Privacy.

Communications metadata can be used to determine a communication's device, identify the user of the device, and profile the user's personality and behavior. The current state of affairs is that the increase of attacks against user privacy based on using communications metadata vastly outpaces the ability of users to protect themselves. With few exceptions, protections are point solutions against a specific attack. In the current situation, the user loses. This paper is an initial step in a multi-step research effort to reset that balance. The main contribution of this paper is a categorization of the uses of communications metadata based on their privacy impact. Because of the technical complexity of the problem, including the wide variety of electronic communications, technology can only go so far in providing solutions to the privacy problems created by the use of communications metadata. Legal and policy intervention will also be needed. This categorization is intended to provide a start in developing legal and policy privacy protections for communications metadata. Along the way, I also provide an explanation for how it is that communications metadata has become so valuable, sometimes surpassing the value of content. This work provides both an intellectual framework for thinking about the privacy implications of the use of communications metadata and a roadmap, with first steps taken, for providing privacy protections for users of electronic communications.